java.util.concurrent.atomic.AtomicLongArray
jdk1.6类 java.util.concurrent.atomic.AtomicLongArray
java.util.concurrent.atomic.AtomicLongArray
- private long rawIndex(int i)
- public AtomicLongArray(int length)
- public AtomicLongArray(long[] array)
- public final int length()
- public final long get(int i)
- public final void set(int i, long newValue)
- public final void lazySet(int i, long newValue)
- public final long getAndSet(int i, long newValue)
- public final boolean compareAndSet(int i, long expect, long update)
- public final boolean weakCompareAndSet(int i, long expect, long update)
- public final long getAndIncrement(int i)
- public final long getAndDecrement(int i)
- public final long getAndAdd(int i, long delta)
- public final long incrementAndGet(int i)
- public final long decrementAndGet(int i)
- public long addAndGet(int i, long delta)
/*
* %W% %E%
*
* Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.util.concurrent.atomic;
import sun.misc.Unsafe;
import java.util.*;
/**
* A {@code long} array in which elements may be updated atomically.
* See the {@link java.util.concurrent.atomic} package specification
* for description of the properties of atomic variables.
* @since 1.5
* @author Doug Lea
*/
/**
* 可以用原子方式更新其元素的 long 数组。
* 有关原子变量属性的描述，请参阅 java.util.concurrent.atomic 包规范。
*/
public class AtomicLongArray implements java.io.Serializable {
private static final long serialVersionUID = -2308431214976778248L;
// setup to use Unsafe.compareAndSwapInt for updates
private static final Unsafe unsafe = Unsafe.getUnsafe();
private static final int base = unsafe.arrayBaseOffset(long[].class);
private static final int scale = unsafe.arrayIndexScale(long[].class);
private final long[] array;
private long rawIndex(int i) {
if (i < 0 || i >= array.length)
throw new IndexOutOfBoundsException("index " + i);
return base + (long) i * scale;
}
/**
* Creates a new AtomicLongArray of given length.
*
* @param length the length of the array
*/
/**
* 创建给定长度的新 AtomicLongArray。
* @param length 该数组的长度
*/
public AtomicLongArray(int length) {
array = new long[length];
// must perform at least one volatile write to conform to JMM
if (length > 0)
unsafe.putLongVolatile(array, rawIndex(0), 0);
}
/**
* Creates a new AtomicLongArray with the same length as, and
* all elements copied from, the given array.
*
* @param array the array to copy elements from
* @throws NullPointerException if array is null
*/
/**
* 创建与给定数组具有相同长度的新 AtomicLongArray，并从给定数组复制其所有元素。
* @param array 从中复制元素的数组
*/
public AtomicLongArray(long[] array) {
if (array == null)
throw new NullPointerException();
int length = array.length;
this.array = new long[length];
if (length > 0) {
int last = length-1;
for (int i = 0; i < last; ++i)
this.array[i] = array[i];
// Do the last write as volatile
unsafe.putLongVolatile(this.array, rawIndex(last), array[last]);
}
}
/**
* Returns the length of the array.
*
* @return the length of the array
*/
/**
* 返回该数组的长度。
* @return 该数组的长度
*/
public final int length() {
return array.length;
}
/**
* Gets the current value at position {@code i}.
*
* @param i the index
* @return the current value
*/
/**
* 获取位置 i 的当前值。
* @param i 索引
* @return 当前值
*/
public final long get(int i) {
return unsafe.getLongVolatile(array, rawIndex(i));
}
/**
* Sets the element at position {@code i} to the given value.
*
* @param i the index
* @param newValue the new value
*/
/**
* 将位置 i 的元素设置为给定值。
* @param i 索引
* @param newValue 新值
*/
public final void set(int i, long newValue) {
unsafe.putLongVolatile(array, rawIndex(i), newValue);
}
/**
* Eventually sets the element at position {@code i} to the given value.
*
* @param i the index
* @param newValue the new value
* @since 1.6
*/
/**
* 最终将位置 i 的元素设置为给定值。
* @param i 索引
* @param newValue 新值
*/
public final void lazySet(int i, long newValue) {
unsafe.putOrderedLong(array, rawIndex(i), newValue);
}
/**
* Atomically sets the element at position {@code i} to the given value
* and returns the old value.
*
* @param i the index
* @param newValue the new value
* @return the previous value
*/
/**
* 以原子方式将位置 i 的元素设置为给定值，并返回旧值。
* @param i 索引
* @param newValue 新值
* @return 以前的值
*/
public final long getAndSet(int i, long newValue) {
while (true) {
long current = get(i);
if (compareAndSet(i, current, newValue))
return current;
}
}
/**
* Atomically sets the value to the given updated value
* if the current value {@code ==} the expected value.
*
* @param i the index
* @param expect the expected value
* @param update the new value
* @return true if successful. False return indicates that
* the actual value was not equal to the expected value.
*/
/**
* 如果当前值 == 预期值，则以原子方式将该值设置为给定的更新值。
* @param i 索引
* @param expect 预期值
* @param update 新值
* @return 如果成功，则返回 true。返回 false 指示实际值与预期值不相等。
*/
public final boolean compareAndSet(int i, long expect, long update) {
return unsafe.compareAndSwapLong(array, rawIndex(i),
expect, update);
}
/**
* Atomically sets the value to the given updated value
* if the current value {@code ==} the expected value.
*
* <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
* and does not provide ordering guarantees, so is only rarely an
* appropriate alternative to {@code compareAndSet}.
*
* @param i the index
* @param expect the expected value
* @param update the new value
* @return true if successful.
*/
/**
* 如果当前值 == 预期值，则以原子方式将该值设置为给定的更新值。
* 可能意外失败并且不提供排序保证，所以只能在很少的情况下对 compareAndSet 进行适当地选择。
* @param i 索引
* @param expect 预期值
* @param update 新值
* @return 如果成功，则返回 true。
*/
public final boolean weakCompareAndSet(int i, long expect, long update) {
return compareAndSet(i, expect, update);
}
/**
* Atomically increments by one the element at index {@code i}.
*
* @param i the index
* @return the previous value
*/
/**
* 以原子方式将索引 i 的元素加 1。
* @param i 索引
* @return 以前的值
*/
public final long getAndIncrement(int i) {
while (true) {
long current = get(i);
long next = current + 1;
if (compareAndSet(i, current, next))
return current;
}
}
/**
* Atomically decrements by one the element at index {@code i}.
*
* @param i the index
* @return the previous value
*/
/**
* 以原子方式将索引 i 的元素减 1。
* @param i 索引
* @return 以前的值
*/
public final long getAndDecrement(int i) {
while (true) {
long current = get(i);
long next = current - 1;
if (compareAndSet(i, current, next))
return current;
}
}
/**
* Atomically adds the given value to the element at index {@code i}.
*
* @param i the index
* @param delta the value to add
* @return the previous value
*/
/**
* 以原子方式将给定值与索引 i 的元素相加。
* @param i 索引
* @param delta 要加上的值
* @return 以前的值
*/
public final long getAndAdd(int i, long delta) {
while (true) {
long current = get(i);
long next = current + delta;
if (compareAndSet(i, current, next))
return current;
}
}
/**
* Atomically increments by one the element at index {@code i}.
*
* @param i the index
* @return the updated value
*/
/**
* 以原子方式将索引 i 的元素加1。
* @param i 索引
* @return 更新的值
*/
public final long incrementAndGet(int i) {
while (true) {
long current = get(i);
long next = current + 1;
if (compareAndSet(i, current, next))
return next;
}
}
/**
* Atomically decrements by one the element at index {@code i}.
*
* @param i the index
* @return the updated value
*/
/**
* 以原子方式将索引 i 的元素减1。
* @param i 索引
* @return 更新的值
*/
public final long decrementAndGet(int i) {
while (true) {
long current = get(i);
long next = current - 1;
if (compareAndSet(i, current, next))
return next;
}
}
/**
* Atomically adds the given value to the element at index {@code i}.
*
* @param i the index
* @param delta the value to add
* @return the updated value
*/
/**
* 以原子方式将给定值添加到索引 i 的元素。
* @param i 索引
* @param delta 要添加的值
* @return 更新的值
*/
public long addAndGet(int i, long delta) {
while (true) {
long current = get(i);
long next = current + delta;
if (compareAndSet(i, current, next))
return next;
}
}
/**
* Returns the String representation of the current values of array.
* @return the String representation of the current values of array.
*/
/**
* 返回数组当前值的字符串表示形式。
* @return 数组当前值的字符串表示形式。
*/
public String toString() {
if (array.length > 0) // force volatile read
get(0);
return Arrays.toString(array);
}
}